1. Field of the Invention
The invention is directed to the field of pressure connectors for electrical conductors and the like.
2. Description of the Prior Art
Various prior art pressure or clamp connectors for coupling an electrical conductor to a further part are exemplified in U.S. Pat. No. 2,132,967 issued to F. Pennell on Oct. 11, 1938; U.S. Pat. No. 2,809,363 issued to G. Schertel et al. on Oct. 8, 1957; U.S. Pat. No. 3,863,414 issued to G. DeAngelo et al. on Aug. 8, 1972; German Pat. No. 1,091,168 (Siemens); and German Pat. No. 1,196,742 (Siemens). Each of these devices, except for the Pennell device, is generally disclosed as providing a resilient spring band housing to maintain pressure on a conductor seated between lower and upper pressure plates. In each case the side walls of the band within which the parts are located are aligned in generally parallel relationship thereby severely limiting the amount of residual resiliency available after the pressure connection has been effected. An attempt to compensate for this shortcoming is disclosed by Schertel and Siemens' 168 whereby the side walls are provided with indented portions for expansion. In each case, however, the encompassing spring band is in a relaxed state prior to the application of force to the connection through the pressure plates so that the reacting force which is available to maintain the conductor in pressure engagement with the pressure plates is limited by the amount of pressure which can be applied by movement of a threaded screw means which is driven against one of the pressure plates. The Schertel and Siemens' 168 devices, although providing a limited amount of extension of the side walls of the spring band, still only provide a limited amount of compression force between the conductor and the pressure plates due to the geometry of these devices since the compressive forces are derived from only a small section of the spring band or enclosure. Accordingly, these prior art devices approach their elastic limit at a relatively low compression force thereby seriously limiting their effectiveness in many cases where high pressure forces are required, such as, for example, where it is necessary to provide a reliable mechanical connection to aluminum cables and the like which have relatively high coefficients of expansion and contraction in comparison with copper, and where the necessity for maintaining high pressure between a terminal and the aluminum surface is necessary to avoid the problems of oxidation and the resulting increase in resistance occasioned thereby.